Method for hydrogenation of polymer

ABSTRACT

A process for hydrogenating a polymer, which process comprises contacting a polymer containing an olefinic unsaturated group with hydrogen in the presence of a hydrogenation catalyst to hydrogenate the olefinic unsaturated group of the polymer, and recycling at least one part of the hydrogenated polymer for hydrogenation. According to the process of the present invention, there can be provided a polymer having a desirable degree of hydrogenation steadily for a long period.

TECHNICAL FIELD

[0001] The present invention relates to a process for hydrogenatingolefinic unsaturated groups by contacting a solution of polymerscontaining the olefinic unsaturated groups with hydrogen in the presenceof a hydrogenation catalyst. More specifically, the present inventionrelates to a process for hydrogenating a polymer wherein at least onepart of a hydrogenated polymer solution is recycled and hydrogenated inthe above-mentioned process.

BACKGROUND ART

[0002] A polymer containing olefinic unsaturated groups hasdisadvantages of being inferior in stability, such as heat resistanceand oxidation resistance due to olefinic unsaturated groups, while theolefinic unsaturated groups are advantageously used for thevulcanization or the like. These disadvantages are remarkably improvedby hydrogenating olefinic unsaturated groups in polymer chains.

[0003] The present applicant has already taught hydrogenation processesusing metallocene type catalysts in Japanese Patent ApplicationLaid-Open Nos. 61-28507, 61-33132, 61-47706 and 62-209103, JapanesePatent Publication Nos. 63-5402 and 1-53851, and the like. Theseinventions relate to a batch hydrogenation process. However, metallocenetype catalysts are not only expensive but also have disadvantages ofbeing easily inactivated by the rise of temperature caused by the heatof the hydrogenation reaction or the like. Owing to these disadvantages,the catalysts have been used in an amount more than necessary orhydrogenation reaction periods have become long. As a result, problemsin production costs have been caused.

[0004] On the other hand, Japanese Patent Application Laid-Open No.8-109219 discloses a production process of a hydrogenated polymer havingan excellent weather resistance wherein a polymer solution containingolefinic unsaturated groups, hydrogen gas, and a hydrogenation catalystare continuously supplied to a tank reactor equipped with a stirrer andthe reaction product is continuously taken out. Japanese PatentApplication Laid-Open No. 11-286513 discloses a continuous productionprocess of a hydrogenated polymer containing olefinic unsaturated groupswherein plural reactors are connected in series and hydrogen is suppliedto at least one of the reactors from the lower portion thereof.

[0005] However, according to these processes, it has been difficult tomaintain and control a desirable degree of hydrogenation in the case ofa long-term continuous operation. Particularly, in the case ofproduction of a highly hydrogenated polymer, a polymer having a lowerdegree of hydrogenation than aimed has been disadvantageously obtained,or the hydrogenation reaction has had to be restarted after thecontinuous hydrogenation reaction is once stopped to adjust thehydrogenation condition when the hydrogenation reaction is not performedproperly. Additionally, in the case of these continuous hydrogenationprocesses, the amount of catalysts used have disadvantageously increasedthough productivity has been higher than a batch hydrogenation process.

[0006] Therefore, it has been strongly desired to develop methods forovercoming these problems.

DISCLOSURE OF THE INVENTION

[0007] An object of the present invention is to provide a process forhydrogenating a polymer containing an olefinic unsaturated group whichcan steadily maintain or control a desirable degree of hydrogenation fora long term.

[0008] The present inventors have studied the above-mentioned problemsextensively and intensively. As a result, the inventors have found thatthe above-mentioned problems can be solved by recycling one part of ahydrogenated polymer solution to the reactor, and thus accomplished thepresent invention.

[0009] Namely, the present invention is:

[0010] (1) A process for hydrogenating a polymer, which processcomprises the steps of:

[0011] contacting a polymer solution containing an olefinic unsaturatedgroup with hydrogen in the presence of a hydrogenation catalyst tohydrogenate the olefinic unsaturated group of the polymer; and

[0012] recycling at least one part of the resultant hydrogenated polymersolution for hydrogenation.

[0013] The present invention also covers the following preferredembodiments.

[0014] (2) The process according to the above-mentioned process (1),wherein the polymer solution containing an olefinic unsaturated group iscontinuously supplied to a reactor to continuously hydrogenate theolefinic unsaturated group of the polymer, and the resultanthydrogenated polymer solution is continuously taken out from the reactorand then one part thereof is continuously recycled to the reactor forhydrogenation.

[0015] (3) The process according to the above-mentioned process (2),wherein the hydrogen is supplied from near the bottom of the reactor.

[0016] (4) The process according to the above-mentioned process (2) or(3), wherein the reactor is a tank reactor, the polymer solutioncontaining an olefinic unsaturated group is supplied from near the topof the reactor, and the resultant hydrogenated polymer solution is takenout from near the bottom of the reactor or a piping arranged out of thereactor to recycle one part thereof to the reactor for hydrogenation.

[0017] (5) The process according to any one of the above-mentionedprocesses (2) through (4), wherein the reactor is a tank reactor havingan L/D of from 1 to 8 and being equipped with a stirrer, wherein Lrepresents a length between an upper tangent line and a lower tangentline of the reactor and D represents an inner diameter of the reactor.

[0018] (6) The process according to the above-mentioned process (2) or(3), wherein the reactor is a column or tube reactor, the polymersolution containing an olefinic unsaturated group is supplied from nearthe bottom of the reactor, and one part of the polymer solutionhydrogenated in the reactor is continuously taken out from near the topof the reactor or a piping arranged out of the reactor to recycle onepart thereof to the reactor.

[0019] (7) The process according to any one of the above-mentionedprocesses (1) through (6), wherein the hydrogenation catalyst issupplied two or more times to conduct hydrogenation.

[0020] (8) The process according to the above-mentioned process (1),wherein a reactor group comprising two or more reactors connected inseries is used, the polymer solution containing an olefinic unsaturatedgroup is continuously supplied to the first reactor of the reactorgroup, the hydrogen is supplied to at least one reactor of the reactorgroup to continuously hydrogenate the olefinic unsaturated group of thepolymer, and the resultant polymer solution hydrogenated in at least onereactor of the reactor group is continuously taken out to continuouslyrecycle one part thereof to the reactor and/or a reactor arrangedupstream of the reactor for hydrogenation.

[0021] (9) The process according to the above-mentioned process (8),wherein the hydrogen is supplied from near the bottom of at least onereactor of the reactor group.

[0022] (10) The process according to the above-mentioned process (8) or(9), wherein the first reactor is a tank reactor having an L/D of from 1to 8 and being equipped with a stirrer, and the second and followingreactors arranged downstream of the first reactor are at least one kindselected from the group consisting of a tank reactor having an L/D offrom 1 to 8 and being equipped with a stirrer, a column reactor havingan L/D of 2 or more and a tube reactor having an L/D of 2 or more.

[0023] (11) The process according to any one of the above-mentionedprocesses (8) through (10), wherein at least one reactor is a tankreactor, the polymer solution containing an olefinic unsaturated groupis supplied to the reactor from near the top thereof, and one part ofthe resultant polymer solution hydrogenated therein is continuouslytaken out from near the bottom of the reactor or a piping arranged outof the reactor and then is recycled to the reactor or a reactor arrangedupstream of the reactor.

[0024] (12) The process according to any one of the above-mentionedprocesses (8) through (10), wherein at least one reactor is a column ortube reactor, the polymer solution containing an olefinic unsaturatedgroup is supplied to the reactor from near the bottom thereof, and onepart of the resultant polymer solution hydrogenated in the reactor iscontinuously taken out from near the top of the reactor or a pipingarranged out of the reactor and then is recycled to the reactor or areactor arranged upstream of the reactor.

[0025] (13) The process according to any one of the above-mentionedprocesses (8) through (13), wherein the hydrogenation catalyst solutionis supplied to the first reactor and is additionally supplied to atleast one of the reactors arranged downstream of the first reactor.

[0026] (14) The process according to any one of the above-mentionedprocesses (2) through (13), wherein the continuous hydrogenation isinitiated after the polymer solution containing an olefinic unsaturatedgroup is hydrogenated to a desirable degree of hydrogenation.

[0027] (15) The process according to any one of the above-mentionedprocesses (1) through (14), wherein the mass ratio between the polymercontaining an olefinic unsaturated group to be supplied to the reactorand the resultant hydrogenated polymer to be recycled is from 1/50 to50/1.

[0028] (16) The process according to the above-mentioned process (1),wherein the hydrogenation reaction is a batch type.

[0029] (17) The process according to the above-mentioned process (16),wherein the hydrogenation catalyst is supplied two or more times.

[0030] (18) The process according to the above-mentioned process (17),wherein timing of the second and following supply of the hydrogenationcatalyst is determined by measuring an absorption rate of hydrogen.

[0031] (19) The process according to the above-mentioned process (18),wherein timing of the second and following supply of the hydrogenationcatalyst is at a time when the absorption rate of hydrogen decreases to80% or less of an initial absorption rate of hydrogen at the beginningof the hydrogenation reaction.

[0032] (20) The process according to the above-mentioned process (17),wherein an amount of the first supply of hydrogenation catalyst iscontrolled so that a degree of hydrogenation at the time of the secondand following supply is from 50% to 90%.

[0033] (21) The process according to any one of the above-mentionedprocesses (1) through (20), wherein the resultant hydrogenated polymersolution is recycled through a heat exchanger.

[0034] (22) The process according to any one of the above-mentionedprocesses (1) through (21), wherein the hydrogenation catalyst is ametallocene compound.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035]FIG. 1 shows a schematic flow of one example of the presentinvention (Example 1).

[0036]FIG. 2 shows a schematic flow of one example of the conventionalprocess (Comparative Example 1).

[0037]FIG. 3 shows a schematic flow of one example of the presentinvention (Example 2).

[0038]FIG. 4 shows a schematic flow of one example of the presentinvention (Example 3).

[0039]FIG. 5 shows a schematic flow of one example of the presentinvention (Example 4).

[0040]FIG. 6 shows a schematic flow of one example of the presentinvention (Example 5).

[0041]FIG. 7 shows a schematic flow of one example of the presentinvention (Example 11).

BEST MODE FOR CARRYING OUT THE INVENTION

[0042] The present invention is a process for hydrogenating a polymerwherein a polymer solution containing an olefinic unsaturated group iscontacted with hydrogen in the presence of a hydrogenation catalyst tohydrogenate the olefinic unsaturated group of the polymer, and ischaracterized in that at least one part of a resultant hydrogenatedpolymer solution is recycled and hydrogenated in the hydrogenationprocess. Heretofore, it has not been known that, by recycling at leastone part of a polymer, which is partially hydrogenated but stillcontains olefinic unsaturated groups, to a zone where a polymer having alower degree of hydrogenation than the polymer to be recycled ishydrogenated to perform a hydrogenation reaction of both of the polymersas proposed in the present invention, a hydrogenation reaction steadilyproceeds so that a hydrogenated polymer having a desirable degree ofhydrogenation is obtainable.

[0043] The inventors have made studies focusing on the fact that, in ahydrogenation reaction of a polymer solution containing an olefinicunsaturated group, the polymer solution is difficult to mix or contactwith hydrogen because of its high viscosity and the reaction is hard toproceed compared with that of a monomer. As a result, the inventors havefound that the stirring effect can be improved by recycling one part ofa polymer, which is partially hydrogenated but still contains olefinicunsaturated groups, to hydrogenate and succeeded in performing thehydrogenation reaction steadily. Moreover, the present inventors havealso found that a catalyst is deactivated not only by rise intemperature but by decrease of unhydrogenated double-bonds in a reactionsystem in the case of hydrogenation using a metallocene catalyst, andsuccessfully achieved a stable hydrogenation reaction by returning thepolymer solution having double-bonds to the reaction system to increasethe double-bonds therein and prevent the catalyst from beingdeactivated.

[0044] The process of the present invention includes a batchhydrogenation process, in which only a polymer solution containing anolefinic unsaturated group which is supplied to a reactor in advance ishydrogenated and taken out from the system after a degree ofhydrogenation reaches a desirable level, and a continuous hydrogenationprocess, in which a polymer solution containing an olefinic unsaturatedgroup is continuously supplied and the hydrogenated polymer solution iscontinuously taken out. Of these, a continuous hydrogenation process ispreferred in that the reaction and a reaction temperature can be easilycontrolled by adjusting the supply speed of the polymer solution.

[0045] The hydrogenation process of the present invention may beconducted by using one reactor or two or more reactors.

[0046] In the case of using one reactor, it is preferred that a polymersolution containing an olefinic unsaturated group is supplied to thereactor from near the top thereof, and hydrogen is supplied to thereactor at near the bottom thereof or a recycle line for the polymersolution, and the resultant hydrogenated polymer solution iscontinuously taken out from near the bottom of the reactor or a pipingarranged out of the reactor and then recycled to the reactor tohydrogenate. In the present invention, the phrases “near the top” and“near the bottom” indicate the top and a position close to the top of areactor, and the bottom and a position close to the bottom of a reactor,respectively. A position to which a hydrogenated polymer solution isrecycled is preferably above the lower tangent line of a reactor, morepreferably above the lower tangent line of a reactor by L/10 or more.Herein, L represents a length between the upper tangent line and thelower tangent line of a reactor (the same applied to the below).

[0047] In the process of the present invention, two or more reactors canbe also used by connecting them in series. In this case, a polymersolution hydrogenated in at least one of the reactors connected inseries is recycled to the reactor and/or a reactor arranged upstream ofthe reactor to hydrogenate. Particularly, recycling is preferablyperformed according to any one of the following manners comprising:

[0048] 1) recycling the polymer solution hydrogenated in the firstreactor to the first reactor,

[0049] 2) recycling the polymer solution hydrogenated in the secondreactor to the first and/or second reactor(s), and

[0050] 3) conducting 1) and 2) in combination.

[0051] When a polymer solution to be hydrogenated is supplied to areactor from near the top thereof, it is preferred that a polymersolution to be recycled is continuously taken out from near the bottomof the reactor or a piping arranged out of the reactor and recycled tothe reactor or another reactor. Such a recycling method is suitable forthe case where the reactor is a tank, column or tube reactor. In thisrecycling method, when the solution is recycled to the same reactor asthe one from which it is taken out, the hydrogenated polymer solution ispreferably recycled to a position above the lower tangent line of thereactor, particularly a position above the lower tangent line of thereactor by L/10 or more. In the case of recycling to another reactor,the position is not particularly limited.

[0052] When a polymer solution to be hydrogenated is supplied to areactor from near the bottom thereof, it is preferred that a polymersolution to be recycled is continuously taken out from near the top ofthe reactor or a piping arranged out of the reactor and recycled to thereactor or another reactor. Such a recycling method is suitable for thecase where the reactor is a column or tube reactor. In this recyclingmethod, when the solution is recycled to the same reactor as the onefrom which it is taken out, the hydrogenated polymer solution ispreferably recycled to a position below the upper tangent line of thereactor, particularly a position below the upper tangent line by L/10 ormore. In the case of recycling to another reactor, the position is notparticularly limited.

[0053] The amount of a polymer solution to be recycled is notparticularly limited in the present invention. A hydrogenated polymersolution being taken out from the reactor may be recycled in the wholeamount or one part thereof. In the case of continuous hydrogenation, ahydrogenated polymer solution being taken out from a reactor ispreferably recycled in an amount of from 1/51 to 50/51 (mass ratio). Inthe case of batch hydrogenation, the whole amount of a hydrogenatedpolymer solution is preferably recycled.

[0054] The ratio (mass ratio) of a polymer, which is recycled from areactor (origin of recycling) to the reactor or another reactor(destination of recycling), to a polymer containing an olefinicunsaturated group, which is supplied to a reactor (origin of recycling)to hydrogenate, is preferably 1/50 or more, more preferably 1/30 ormore, most preferably 1/25 or more from the viewpoint of stability of ahydrogenation reaction or a degree of hydrogenation of the obtainedpolymer, and is preferably 50/1 or less, more preferably 30/1 or less,most preferably 25/1 or less from the viewpoint of commercialproductivity. This mass ratio is adjustable by changing the amount of apolymer solution to be recycled or the amount of a polymer solution tobe supplied to the hydrogenation reactor.

[0055] The degree of hydrogenation of a polymer to be recycled ispreferably 3% or more and less than 100%, more preferably from 5 to99.5%, most preferably from 10 to 99%. Here, the degree of hydrogenationcan be measured by the methods described below.

[0056] In the present invention, a polymer solution to be recycled maybe recycled through a piping equipped with a heat exchanger to control areaction temperature in a reactor to which the polymer solution to berecycled is supplied. This process is effective for the case where ahydrogenation temperature is difficult to control by a jacket or aninternal cooling coil, and also for the case of controlling ahydrogenation temperature at an initial period of the hydrogenationreaction wherein a large quantity of reaction heat is generated orcontrolling the hydrogenation temperature of a polymer solution having ahigh viscosity.

[0057] The polymer containing an olefinic unsaturated group in thepresent invention is a polymer to be hydrogenated, and includes a rawmaterial, i.e., a polymer containing an olefinic unsaturated group whichis not hydrogenated at all, and a polymer containing an olefinic groupwhich is hydrogenated to some extent and still contains remainingolefinic unsaturated groups.

[0058] The polymer containing an olefinic unsaturated group in thepresent invention is a conjugated diene polymer, a random, tapered orblock copolymer of a conjugated diene and a vinyl aromatic compound, ora composition containing them at an arbitrary ratio. Also, itincorporates conjugated dienes through 1,4-, 1,2- or 3,4-bonds, andcontains olefinic unsaturated groups derived from the conjugated dienes.The addition position of the conjugated diene unit in the polymercontaining the olefinic unsaturated group includes 1,2-, 3,4-and1,4-addiition. The ratio thereof is not particularly limited. Theprocess of the present invention can apply to any of the positions.

[0059] The conjugated diene includes a conjugated diene having from 4 to20 carbon atoms, specifically 1,3-butadiene, isoprene,2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene,1,3-hexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene and thelike. From the viewpoint of industrial advantages and the preparation ofelastic products having excellent physical properties, 1,3-butadiene andisoprene are preferred. Examples of the vinyl aromatic compound includestyrene, α-methylstyrene, p-methylstyrene, divinylbenzene,1,1-diphenylethylene, N,N-dimethyl-p-aminoethylstyrene,N,N-diethyl-p-aminoethylstyrene and the like. The preferred is styreneand α-methylstyrene.

[0060] In the present invention, when the polymer containing an olefinicunsaturated group is a copolymer of a conjugated diene and a vinylaromatic compound, the ratio of these compounds in the polymer ispreferably from 5/95 to 95/5 based on mass ratio.

[0061] The conjugated polymer or the random or tapered copolymer of theconjugated dienes and the vinyl aromatic compound usable in the presentinvention has a number average molecular weight of preferably from10,000 to 3,000,000, more preferably from 50,000 to 1,500,000.

[0062] The block copolymer usable in the present invention includesblock copolymers represented by any one of the following generalformulas and arbitrary compositions thereof.

(A—B)_(n), A—(B—A)_(n), B—(A—B)_(n), [(B—A)_(n)]_(m+1)—X,

[(A—B)_(n)]_(m+1)—X, [(B—A)_(n)—B]_(m+1)—X, and [(A—B)_(n)—A]_(m+1—X)

[0063] (In the above-listed formulas, A represents a polymer blockmainly composed of vinyl aromatic hydrocarbons, and B represents apolymer block mainly composed of conjugated dienes. The boundary of Ablock and B block is not necessary to clearly distinguish. Moreover, nis 1 or more, preferably an integer of from 1 to 5. X represents, forexample, a residue of a coupling agent such as a polyhalogenated organicsilicon compound like silicon tetrachloride, a polyhalogenated organictin compound like tin tetrachloride, epoxidized soybean oil, a compoundhaving from 2 to 6 functional epoxy groups, polyhalogenated hydrocarbon,carboxylic acid ester, and a polyvinyl compound such as divinylbenzene,dialkyl carbonates like dimethyl carbonates; or a residue of aninitiator such as a polyfunctional organic lithium compound. m is 1 ormore, preferably an integer of from 1 to 10.)

[0064] In the above-mentioned formulas, the term “polymer block mainlycomposed of vinyl aromatic hydrocarbons” generally means a copolymerblock of vinyl aromatic hydrocarbons and conjugated dienes whichcontains 50 wt % or more, preferably 70 wt % or more, of the vinylaromatic hydrocarbons, and/or a homopolymer block of vinyl aromatichydrocarbons. The term “polymer block mainly composed of conjugateddienes” generally means a copolymer block of conjugated dienes and vinylaromatic hydrocarbons which contains 50 wt % or more, preferably 70 wt %or more, of the conjugated dienes, and/or a homopolymer block ofconjugated dienes. The vinyl aromatic hydrocarbons in the copolymerblock may be distributed uniformly or in the tapered form. There maycoexist parts in which vinyl aromatic hydrocarbons are distributeduniformly and those in which vinyl aromatic hydrocarbons are distributedin the tapered form. The polymer block mainly composed of vinyl aromatichydrocarbons has a number average molecular weight of preferably from5,000 to 300,000, more preferably from 7,000 to 200,000. The polymerblock mainly composed of conjugated dienes has a number averagemolecular weight of preferably from 5,000 to 500,000, more preferablyfrom 10,000 to 300,000. The number average molecular weight of theentire block copolymer is preferably from 20,000 to 1,000,000, morepreferably from 30,000 to 800,000. In the present invention, the numberaverage molecular weight is obtained by conducting measurementsaccording to gel permeation chromatography (GPC) and obtaining a peakmolecular weight of chromatogram using a working curve which is obtainedby measuring a standard polystyrene on the market (which is preparedusing a peak molecular weight of the standard polystyrene).

[0065] A polymer containing an olefinic unsaturated group may beprepared, for example, by polymerization in an inert hydrocarbon solventusing an organic alkali metal compound as an initiator. Herein, theinert hydrocarbon solvent indicates a solvent which does not adverselyaffect the reaction of polymerization or hydrogenation of a polymercontaining an olefinic unsaturated group. Although the inert hydrocarbonsolvents used in the steps of polymerization and hydrogenation may bedifferent in composition, it is preferable to conduct hydrogenationsubsequent to polymerization in the same inert hydrocarbon solvent asused in the polymerization. Preferred solvents include aliphatichydrocarbons such as n-butane, isobutane, n-pentane, n-hexane,n-heptane, and n-octane; alicyclic hydrocarbons such as cyclohexane,cycloheptane, and methylcycloheptane; and aromatic hydrocarbon such asbenzene, toluene, xylene, and ethylbenzene. When an aromatic hydrocarbonis employed as a solvent, it is preferable to use such a solvent underthe condition where aromatic double bonds are not hydrogenated.

[0066] Organoalkali metallic compounds used as polymerization initiatorsfor a polymer containing an olefinic unsaturated group include aliphatichydrocarbon alkalimetallic compounds, aromatic hydrocarbonalkalimetallic compounds, organoamino alkalimetallic compounds and thelike, and alkali metals include lithium, sodium, potassium and the like.Preferred organoalkali metallic compounds include aliphatic or aromatichydrocarbon lithium compounds having from 1 to 20 carbon atoms, i.e.,compounds containing one lithium per molecule and those having two ormore lithium per molecule such as dilithium compounds, trilithiumcompounds and tetralithium compounds. Specifically, there can beexemplified n-propyl lithium, n-butyl lithium, sec-butyl lithium,tert-butyl lithium, n-pentyl lithium, n-hexyl lithium, benzyl lithium,phenyl lithium, tolyl lithium, a reaction product ofdiisopropenylbenzene and sec-butyl lithium, a reaction product ofdivinylbenzene, sec-butyl lithium and a small amount of 1,3-butadiene,and the like. In addition, 1-(t-butoxy) propyl lithium and a lithiumcompound introducing from one to several isoprene monomers to improveits solubility which are disclosed in U.S. Pat. No. 5,708,092; alkyllithium containing siloxy groups such as 1-(t-butyldimethylsiloxy)hexyllithium which is disclosed in British Patent No. 2,241,239; and aminolithiums such as alkyl lithium containing amino groups, diisopropylamide lithium and hexamethyldisilazide lithium which are disclosed inU.S. Pat. No. 5,527,753 can be used.

[0067] When a polymer containing an olefinic unsaturated group isprepared by polymerization of conjugated diene or that of conjugateddiene and a vinyl aromatic compound using an organoalkali metalliccompound as a polymerization initiator, a tertiary amine compound orether compound can be added to increase vinyl structure of theconjugated diene (1,2- or 3,4-bonds). As examples of tertiary aminecompounds, there can be exemplified compounds represented by the generalformula, R¹R²R³N, wherein R¹, R², and R³ represent hydrocarbon groupshaving from 1 to 20 carbon atoms or those having tertiary amino groups.Examples of these compounds include trimethylamine, triethylamine,tributylamine, N,N-dimethylaniline, N-ethylpiperidine,N-methylpyrolidine, N,N,N′,N′-tetramethylethylenediamine,N,N,N′,N′-tetraethylethylenediamine, 1,2-dipiperidinoethane, trimethylaminoethylpiperazine, N,N,N′,N″,N″-pentamethylethylene triamine,N,N′-dioctyl-p-phenylenediamine and the like. The ether compounds may beeither a straight-chain ether compound or a cyclic ether compound.Examples of the straight-chain ether compound include dimethyl ether;diethyl ether; diphenyl ether; dialkyl ether compounds of ethyleneglycol such as ethylene glycol dimethyl ether, ethylene glycol diethylether and ethylene glycol dibutyl ether; dialkyl ether compounds ofdiethylene glycol such as diethylene glycol dimethyl ether, diethyleneglycol diethyl ether and diethylene glycol dibutyl ether; and the like.Examples of the cyclic ether compound include tetrahydrofuran, dioxane,2,5-dimethyl oxorane, 2,2,5,5-tetramethyl oxorane,2,2-bis(2-oxoranyl)propane, alkyl ether of furfuryl alcohol, and thelike.

[0068] Polymers containing olefinic unsaturated groups may be preparedeither by batch polymerization or continuous polymerization.

[0069] Living growth ends of polymers containing olefinic unsaturatedgroups are preferably deactivated by a deactivator prior tohydrogenation for the purpose of restraining metallation reactions orthe like among polymer chains which causes formation of macromoleculesor gelation. Instead of the deactivation, a multifunctional compoundhaving two or more functional groups in one molecule may be added to thepolymer to form a branched or star polymer.

[0070] Although deactivators are not particularly limited, those likehydroxyl, carbonyl, ester, and epoxy groups, which generate alkoxymetals by reaction with organometallic compounds, or those likehalogenated compounds, which generate metal halides, are preferred. Insome cases, compounds having ester, ketone, aldehyde, isocyanate, amino,imino or acid anhydride groups, polyepoxy compounds or polyhalogenatedcompounds may be used. These compounds may be also used for the purposeof adding polar groups to polymer ends by reaction with alkali metalends of the polymer, or for the purpose of either increase in amolecular weight or production of branches by coupling. Examples ofdeactivators include water, hydrogen, carbon dioxide gases and the likein addition to (polyvalent) alcohols, (polyvalent) phenols, organiccarboxylic acids, organic carboxylic anhydrides, organic carboxylic acidesters, ketones, epoxy compounds and the like. These deactivators may beused alone or in combination.

[0071] Solvents of a polymer solution containing olefinic unsaturatedgroups are inert hydrocarbon solvents, and include the same solvents asused for the polymerization of a polymer containing olefinic unsaturatedgroups.

[0072] Solvents of a polymer solution containing olefinic unsaturatedgroups or solvents being used for the polymerization may containcompounds containing unsaturated groups like butenes, such as 1-buteneor isobutene at a content, for example, of 30 wt % or less. However,since one part of the butenes are hydrogenated, it is preferable toreduce the content of butenes in the polymer solution containingolefinic unsaturated group to as small as possible by an operation likeflushing before a hydrogenation reaction.

[0073] The concentration of a polymer in the polymer solution containingolefinic unsaturated groups is preferably 5 wt % or more, morepreferably 10 wt % or more from the viewpoint of energy load at thepost-processing for the separation of the hydrogenated polymer and thesolvent and a production cost. From the viewpoint of miscibility withhydrogen, hydrogenation catalysts or the like and heat transferproperty, it is preferably 40 wt % or less, more preferably 30 wt % orless.

[0074] The hydrogenation catalyst used for the process of the presentinvention is not particularly limited, and examples thereof include (1)a supported heterogeneous hydrogenation catalyst, which comprises ametal such as nickel, platinum, palladium and ruthenium supported bycarbon, silica, alumina, diatomaceous earth or the like, (2) a so-calledZiegler type hydrogenation catalyst, which uses transition metal saltlike organic acid salt or acetylacetone salt of nickel, cobalt, iron,chromium or the like, and a reducing agent like organoaluminum, (3) aso-called homogeneous hydrogenation catalyst such as an organometalliccomplex of an organometallic compound of titanium, ruthenium, rhodium,zirconium or the like. Among them, a preferred hydrogenation catalyst isa titanocene compound or a mixture of a titanocene compound and areducible organometallic compound. As a titanocene compound, compoundsdescribed in Japanese Patent Application Laid-Open No. 8-109219 may beused. Specific examples thereof include compounds containing at leastone ligand having (substituted) cyclopentadienyl frames such asbiscyclopentadienyl titanium dichloride andmonopentamethylcyclopentadienyl titanium trichloride, indenyl frames orfluorenyl frames. Examples of the reducible organometallic compoundsinclude an organoalkalimetalic compound like organolithium, anorganomagnesium compound, an organoaluminum compound, an organic boroncompound, an organozinc compound or the like.

[0075] The present invention exhibits its effects more sufficiently whenmetallocene compounds are used as a hydrogenation catalyst. Themetallocene hydrogenation catalysts are organometallic compounds oftitanium, zirconium, hafnium or the like having same or different two(substituted) cyclopentadienyl groups as a ligand, and are preferablyused with reducible organometallic compounds such as alkyllithium,alkylsodium, alkylpotassium, alkylmagnesium, alkylaluminum andalkylzinc.

[0076] Among the metallocene hydrogenation catalysts, a titanocenecatalyst is preferable. Preferred examples of the hydrogenation processusing a titanocene catalyst include a process for hydrogenating olefincompounds using specific titanocene compounds and alkyllithium (JapanesePatent Application Laid-Open Nos. 61-33132 and 1-53851), a process forhydrogenating olefinic unsaturated (co-)polymers using metallocenecompounds and organoaluminum, organozinc or organomagnesium (JapanesePatent Application Laid-Open Nos. 61-28507 and 62-209103), a process forhydrogenating living polymers containing olefinic unsaturated groupsusing specific titanocene compounds and alkyllithium (Japanese PatentApplication Laid-Open Nos. 61-47706 and 63-5402), a process forhydrogenating olefinic double bonds in polymers containing olefinicunsaturated double bonds using Tebbe reagents, i.e., metallacycliccompounds of a titanocene compound and trimethylamluminum (JapanesePatent Application Laid-Open No. 11-71426), a process for hydrogenatingolefinic double bonds in polymers containing olefinic unsaturated doublebonds using titanocene compounds and a specific amount of lithiumalkoxide (Japanese Patent Application Laid-Open No. 1-275605) or thelike. Hydrogenation conditions may be adopted from those suitablydescribed for each of the above catalysts in the respectivespecification.

[0077] The addition amount of a hydrogenation catalyst is preferably0.001 mmol or more per 100 g of the polymer containing olefinicunsaturated groups from the viewpoint of efficient hydrogenation ofolefinic unsaturated groups. From the viewpoint of deliming or removalof a catalyst after the hydrogenation reaction and economicalefficiency, it is preferably 5 mmol or less per 100 g of the polymercontaining olefinic unsaturated groups. The addition amount of thecatalyst is more preferably from 0.002 to 1 mmol, furthermore preferably0.005 to 0.2 mmol per 100 g of the polymer containing olefinicunsaturated groups.

[0078] Hydrogenation catalysts are generally supplied to a reactor inthe form of a solution. Any solvents can be employed as long as they donot adversely affect hydrogenation. They include, for example, aliphatichydrocarbons such as n-pentane, n-hexane, n-heptane and n-octane;alicyclic hydrocarbons such as cyclohexane, cycloheptane,methylcyclohexane and methylcycloheptane; and aromatic hydrocarbons suchas benzene, toluene, xylene and ethylbenzene. These solvents may containcyclic or straight-chain ethers such as tetrahydrofuran, dimethyl ether,diethyl ether, dimethoxy ethane, diethoxy ethane, dibutoxy ethane,diethylene glycol dimethyl ether, diethylene glycol diethyl ether anddiethylene glycol dibutyl ether, or tertiary amines such astriethylamine and tetramethylethylene diamine in a small amount, withinthe range where the purpose of this invention is not ruined. Theconcentration of a hydrogenation catalyst is not particularly limited.For example, when the hydrogenation catalyst is a metallocene compounds,it is preferably used in the form of a metallocene complex with aconcentration of from 1 to 10 wt %. A higher concentration may beadopted when the solubility is higher.

[0079] The hydrogenation catalysts may be supplied to a hydrogenationreactor either separately from the polymer solution containing olefinicunsaturated groups or after being mixed with the polymer solutioncontaining olefinic unsaturated groups or with a hydrogenated polymersolution to be recycled.

[0080] Hydrogenation catalysts are preferably supplied to a reactor intwo or more times or continuously to restrain a rapid exothermicreaction and stabilize the hydrogenation reaction, by which a catalystamount to be supplied and a reaction period are reduced so that thehydrogenation reaction can be performed more efficiently. Such asupplying method exhibits its effects especially at the hydrogenationusing a metallocene hydrogenation catalyst which is easy to deactivateby decomposition, dimerization or the like at a raised reactiontemperature. Moreover, the effects of the supplying method is remarkablyexhibited in a large-sized industrial reactor since such a reactor isdifficult to cool down.

[0081] In a continuous hydrogenation process, hydrogenation catalystsare preferably supplied to a reactor continuously as well as the polymersolutions containing olefinic unsaturated groups. The reason is that thereaction and reaction temperature are comparatively easy to control byadjusting the supplying rate. In addition, it is also preferable tosupply the hydrogenation catalysts in two or more times. In a continuoushydrogenation process, the hydrogenation catalysts may be suppliedaccording to the following manners. When one hydrogenation reactor isused, a solution of hydrogenation catalyst is continuously supplied tothe reactor. When two or more hydrogenation reactors connected in seriesare used, a solution of hydrogenation catalyst is continuously suppliedto a first reactor, or a solution of hydrogenation catalyst iscontinuously supplied to a first reactor and further continuously orintermittently supplied to at least one reactor arranged downstream ofthe first reactor. The amount of additional supply of the hydrogenationcatalyst can be properly set so as to achieve a target degree ofhydrogenation in each reactor.

[0082] In a batch hydrogenation process, hydrogenation catalysts arepreferably supplied not all at one time but either several times bysmall amounts, or continuously or intermittently by small amounts torestrain a rapid hydrogenation reaction at the initial stage and controla reaction temperature.

[0083] When hydrogenation catalysts are supplied two or more times, theamount of the first supply is not necessary to be an ordinary amount tocomplete the hydrogenation reaction by one supply, rather preferablyless than the ordinary amount. A preferred amount of the first supply issuch that it attains a degree of hydrogenation of from 50 to 90%, forexample, it is 70% or less, particularly 50% or less of the ordinaryamount. Although the hydrogenation reaction may stop halfway in the caseof such a small amount of the catalyst, the reaction continues bysupplying the catalyst additionally, and, as a result, the hydrogenationreaction can complete in a short time with a small amount of thehydrogenation catalyst.

[0084] When hydrogenation catalysts are supplied in two or more times,the timing of the additional supply of hydrogenation catalyst ispreferably judged from an absorption rate of hydrogen. The absorptionrate can be obtained, for example, by measuring an amount of hydrogensupplied to a reactor. If the pressure or temperature of a reactorchanges, the absorption rate of hydrogen is obtainable by calculatingthe amount of hydrogen remaining in a reactor according to an amendedpressure or temperature and subtrating the remaining amount from thesupplied amount of hydrogen. Further, it is also possible to introduce anecessary amount of hydrogen to a reactor in advance and obtain theabsorption rate by measuring pressure reduction of the reactor, thoughcontrol of the hydrogenation reaction becomes slightly difficult.

[0085] When hydrogenation catalysts are supplied two or more times,timing of the second and following supply is preferably at a time whenan absorption rate of hydrogen reduces to 80% or less, more preferably60% or less, of an initial absorption rate of hydrogen at the beginningof reaction from the viewpoint of the addition amount of the catalystand the hydrogenation reaction period. Here, an “initial absorption rateof hydrogen at the beginning of reaction” means at the time when theabsorption rate of hydrogen becomes steady after the initiation of thehydrogenation reaction. Generally, the stable absorption rate isexhibited several minutes after the hydrogenation reaction is started.As long as the degree of hydrogenation exceeds a prescribed value, it isnot necessary to additionally supply the hydrogenation catalyst even ifthe absorption rate of hydrogen is reduced. Though, a small amount ofthe hydrogenation catalyst may be additionally supplied to obtain ahigher degree of hydrogenation.

[0086] The above-mentioned supplying method of a catalyst isparticularly useful in the case of using a metallocene hydrogenationcatalyst. In the process for hydrogenating a polymer containing olefinicunsaturated groups using metallocene compound as a catalyst, thehydrogenation reaction rate shifts almost constantly without dependingon the progress of the hydrogenation reaction, and it tends to be ratheraccelerated in the latter half of the reaction. Therefore, by observingthe absorption rate of hydrogen, it becomes possible to anticipate adegree of deterioration of the hydrogenation catalyst and judgenecessity and timing of additional supply of catalyst adequately.

[0087] The timing of additional supply of hydrogenation catalysts isreproducible in many cases if the conditions are the same. Inhydrogenation processes under the same conditions, after weighing timingof additional supply by absorption rate of hydrogen once or severaltimes according to the above-mentioned manner and confirming an adequatetiming, other management indexes, e.g., time, degree of hydrogenation orreaction temperature, may be employed to decide the timing instead ofthe absorption rate of hydrogen.

[0088] In the present invention, the amount of additional supply of thehydrogenation catalyst may be properly selected according to the amountof remaining olefinic unsaturated groups. If the amount of the remainingolefinic unsaturated group is large at the time of additional supply ofthe catalyst, a large amount of the catalyst is additionally supplied.If it is small, a small amount is supplied. Specifically, an amount ofadditional supply is not more than the same amount of the catalyst asinitially supplied, preferably not more than 70% thereof.

[0089] When hydrogenation catalysts are supplied in two or more times,the number of supply is not particularly limited. However, hydrogenationcatalysts are supplied in preferably from 2 to 10 times, more preferablyfrom 2 to 5 times, including the first supply from the viewpoint ofstability and operationality of the hydrogenation reaction.

[0090] It is acceptable that the hydrogenation catalyst of the firstsupply is activated after being mixed with a conjugated diene polymer.The additional supply is preferably made after the hydrogenationactivity is exhibited or in the state where the catalyst is immediatelyactivated in the hydrogen atmosphere.

[0091] Although the hydrogenation catalysts of the first supply andadditional supply may be different, it is preferable to use the same onefrom the viewpoint of simplicity of the operation.

[0092] The hydrogenation reaction of the present invention is carriedout in the hydrogen atmosphere. Hydrogen is preferably supplied to thepolymer solution containing olefinic unsaturated groups in the form of agas, and it may contain inert gas such as nitrogen and argon within therange where the purpose of this invention is not impaired. Herein, theinert gas indicates a gas which does not react with a hydrogenationcatalyst so that it does not cause deactivation of the catalyst.

[0093] Hydrogen is preferably supplied so as to disperse finely in aliquid phase in order to contact with the polymer containing olefinicunsaturated groups efficiently. To disperse hydrogen in the liquid phaseefficiently finely, equipment like an atomizer can be used. Hydrogen ispreferably supplied to a reactor from near its bottom. The unreactedhydrogen is preferably collected and recycled from the viewpoint of aproduction cost. For example, the unreacted hydrogen of the suppliedhydrogen may be collected from the gas phase in the reactor with solventvapor, separated from the solvent in the solvent collecting tank, andpressurized in a compressor to recycle. In addition, the hydrogen whichis dissolved in the polymer solution may be separated and collectedthrough a flash tank or the like, and pressurized in the compressor torecycle.

[0094] The pressure of hydrogen to be used for the hydrogenationreaction is preferably 0.1 MPa or more from the viewpoint of ahydrogenation speed, and also 15 MPa or less from the viewpoint ofrestraint of a side reaction and costs for equipping a hydrogenationreactor with high pressure resistance strength. The pressure of hydrogenis more preferably from 0.2 MPa to 10 MPa, furthermore preferably from0.3 MPa to 5 MPa. The most suitable pressure of hydrogen is decided inrelation to an amount of the catalyst to be added or the like.Substantially, it is preferred to select a higher pressure of hydrogenas the amount of the catalyst to be supplied becomes smaller. Thepressure of hydrogenation is appropriately selected according to adesirable degree of hydrogenation within the above-mentioned range. Whentwo or more reactors connected in series are used, the pressure of eachreactors may be the same or different. Generally, it is preferred thatthe pressure differential between reactors is smaller, e.g., preferably2 MPa or less, more preferably 1 MPa or less, most preferably 0.5 MPa orless from the viewpoint of smooth transportation of the polymersolution.

[0095] As a hydrogenation reactor, for example, tank, column and tubereactors and the like may be used, and is not particularly limited. Whenone reactor is used as a hydrogenation reactor, a tank reactor which hasan L/D of from 1 to 8 and is equipped with a stirrer is preferably used.Herein, L represents a length between the upper tangent line and thelower tangent line of a reactor and D represents the inside diameter ofthe reactor. When plural reactors are connected to use, it is preferredthat a tank reactor having an L/D of from 1 to 8 and equipped with astirrer is used as a first reactor and a tank reactor having an L/D offrom 1 to 8 and equipped with a stirrer, or a column or tube reactorhaving an L/D of from 2 or more, preferably 3 or more, and morepreferably 5 or more is used as second and following reactors arrangeddownstream of the first reactor. In the case where a column or tubereactor is used, a reactor having a larger L/D is preferred in order tomake the distribution of degree of hydrogenation as narrow as possibleand to obtain a polymer having a comparatively uniform degree ofhydrogenation. For such a purpose, a reactor having an extremely largeL/D like a loop reactor may be used. From the industrial viewpoint,i.e., from the viewpoint of operationality and cleaning of a reactor,the L/D of a column or tube reactor is preferably 50 or less, morepreferably 30 or less, furthermore preferably 20 or less.

[0096] Although it is not necessary to employ a reactor equipped with astirrer, the hydrogenation reaction is preferably conducted withstirring to promptly contact the supplied hydrogen with a polymercontaining olefinic unsaturated groups, and a reactor equipped with astirrer having high stirring ability is preferably used. Especially, ata time when a large amount of hydrogen is consumed, e.g., at the initialstage of a reaction in batch hydrogenation or at continuoushydrogenation having a high production speed, the hydrogenation ispreferably performed while stirring from the viewpoint of uniformity ofhydrogenation reactions, removal of reaction heat or prevention ofregional and abnormal reactions. As a stirrer, any type such as aturbine type, a paddle type, a screw type, an anchor type, a full zonetype or a static type may be used. Generally, in order to disperse a gasinto a liquid phase finely, a disc turbine or paddle type stirrer iseffective and most preferred. When a stirring speed cannot be increased,it is effective to install a ringed sparger right under a stirringblade. A stirring blade may be arranged vertically in a multiple stage.In addition, a flat perforated plate, a baffle plate or the like may beinstalled in the reactor if necessary. When a tube reactor is used, astatic type stirrer is preferred. A static mixer element may beinstalled in the piping.

[0097] The temperature of the hydrogenation reaction may be properlyselected according to the kind of a catalyst or the like. It ispreferably 0° C. or higher from the viewpoint of a reaction rate or theamount of a catalyst used, and is preferably 200° C. or lower from theviewpoint of restraint of a side reaction, decomposition or gelation ofpolymer chains, or catalyst activities. More preferred temperature rangeis from 30° C. to 150° C., particularly from 50° C. to 130° C.

[0098] In the case of a continuous hydrogenation process, an averageresidence time of hydrogenation may be properly selected in view of theoperation stability, productivity and a target degree of hydrogenation.In general, it is preferably from 3 minutes to 10 hours, more preferablyfrom 10 minutes to 5 hours, most preferably from 30 minutes to 3 hours.

[0099] In the case of a continuous hydrogenation process, it ispreferred that a polymer containing olefinic unsaturated groups ishydrogenated in a reactor beforehand to achieve a degree ofhydrogenation at a desirable level and then continuous hydrogenationreaction is commenced, since a polymer having a desirable degree ofhydrogenation can be prepared from the initial stage of the operation.On the other hand, in the case where it is attempted to prepare apolymer having a high degree of hydrogenation by continuoushydrogenation from the beginning of the reaction but a large amount of apolymer other than a polymer having an objective degree of hydrogenationis obtained at the initial stage of the operation, treatment of theobtained polymer is preferably conducted.

[0100] The degree of hydrogenation of the hydrogenated polymer obtainedby the process of the present invention may be properly selectedaccording to the purposes and is not particularly limited. The olefinicunsaturated groups contained in the polymer containing olefinicunsaturated groups may be hydrogenated either almost in the whole (at adegree of hydrogenation of 90% or more, preferably 98% or more inaccordance with 1H-NMR) or only in one part. When only one part ishydrogenated, the degree of hydrogenation is preferably controlled by anamount of hydrogen supplied to a reactor so as to be 3% or more and lessthan 95%, or 5% or more and less than 90%, if desired from 10% to 85%.It can be also controlled by deactivating a hydrogenation catalyst atthe time when the degree of hydrogenation reaches a desirable level.When the degree of hydrogenation is controlled within the range of 3% ormore and less than 95%, the desirable degree of hydrogenation can becharacteristically achieved even if the amount of a hydrogenationcatalyst is 90% or less, further 80% or less or 60% or less, of thatused in the case where the degree of hydrogenation is controlled withinthe range of 95% or more. The degree of hydrogenation can be easilymeasured by using 1H-NMR. In addition, the degree of hydrogenation maybe measured by comparing with a pre-hydrogenated polymer using FT-IR.

[0101] From the polymer solution subjected to the hydrogenation reactionaccording to the process of the present invention, a catalyst residuemay be removed to separate a hydrogenated polymer from solution ifnecessary. Examples of separation methods include a method comprisingcollecting a precipitated polymer obtained by adding a polar solvent, apoor solvent for a hydrogenated polymer such as acetone and alcohol, toa reaction liquid after hydrogenation; a method comprising collecting ahydrogenated polymer by putting a reaction liquid to hot water withstirring and removing a solvent therefrom by steam stripping, a methodcomprising removing a solvent by direct heating of a reaction liquid;and the like.

EXAMPLE

[0102] Hereinafter the present invention is specifically illustratedreferring to Examples, but it is not limited thereto.

[0103] Schematic flows of Examples 1 through 5 and 11 and ComparativeExample 1 are shown in FIGS. 1 through 7. In these figures, 1 and 1′represent supply lines for a hydrogenation catalyst; 2 represents asupply line for a polymer solution containing olefinic unsaturatedgroups; 3, 3′ and 3″ represent supply lines for hydrogen; 4 represents adischarge line for a hydrogenated polymer solution; 5 and 5′ representrecycle lines for the hydrogenated polymer solution; 6, 6′ and 6″represent reactors; and 7 and 7′ represent heat exchangers.

[0104] Methods for measuring physical properties and preparationexamples of polymers and hydrogenation catalysts in Examples andComparative Examples are described below.

[0105] 1) Measurement of Physical Properties of a Polymer ContainingOlefinic Unsaturated Groups

[0106] 1-1) Content of Styrene

[0107] Calculated from absorption strength of 262 nm using a ultravioletray spectrophotometer (UV200, manufactured by Hitachi, Ltd.)

[0108] 1-2) Peak Molecular Weight and Composition Ratio

[0109] Measured by GPC (LC-10 AD, manufactured by Simadzu Corporation)using tetrahydrofuran as a solvent at 35° C. The peak molecular weightwas a molecular weight at the peak of chromatogram which was obtainedusing a working curve prepared by measuring commercially availablestandard styrene (trade name: Polystyrene Standards, manufactured byAmerican Polymer Standards Corporation). When a polymer consists of twoor more components, a composition ratio was obtained by a ratio of areasat the peak of chromatogram of each component.

[0110] 1-3) Content of Vinyl Bonds and Degree of Hydrogenation

[0111] Measured using a nuclear magnetic resonance device (DPX-400,manufactured by BRUKER Corporation).

[0112] 2) Preparation Examples of a Polymer Containing OlefinicUnsaturated Groups

[0113] 2-1) Polymer A

[0114] In a jacketed autoclave equipped with a stirrer, which wasalready washed, dried and substituted with nitrogen, were charged acyclohexane solution containing 10 parts by mass of pre-refined styrene.Then, n-butyllithium and tetramethylethylenediamine were added andpolymerization was carried out at 70° C. for 1 hour. The polymerizationwas continued for 1 hour after adding a cyclohexane solution containing80 parts by mass of pre-refined butadiene and further for 1 hour afteradding a cyclohexane solution containing 10 parts by mass of styrene.After that, methanol was added to stop the reaction. A block copolymerhaving a styrene content of 20 wt %, a 1,2-vinyl bond content inpolybutadiene parts of 40wt % and a number-average molecular weight of100,000 was prepared.

[0115] 2-2) Polymer B

[0116] Polymerization was conducted in the same manner as in thepreparation of Polymer A to prepare a block copolymer which had astyrene content of 30 wt %, a 1,2-vinyl bond content in polybutadieneparts of 45 wt % and a number-average molecular weight of 300,000.

[0117] 2-3) Polymer C

[0118] In a jacketed autoclave equipped with a stirrer, which wasalready washed, dried and substituted with nitrogen, were charged acyclohexane solution containing 30 parts by mass of pre-refined styrene.Then, n-butyllithium and tetramethylethylenediamine were added andpolymerization was carried out at 70° C. for 1 hour. The polymerizationwas continued for 1 hour after adding a cyclohexane solution containing70 parts by mass of pre-refined butadiene. After that,dichlorodimethylsilane was added to carry out a coupling reaction. To apolymer which was not partially deactivated was added methanol to stopthe reaction. The obtained polymer was a block copolymer having astyrene content of 30 wt % and a 1,2-vinyl bond content in polybutadieneparts of 40 wt %, and a molecular weight and content of coupled highmolecular weight components of 140,000 and 30 wt %, respectively, and amolecular weight and content of uncoupled low molecular weightcomponents of 70,000 and 70 wt %, respectively.

[0119] 2-4) Polymer D

[0120] In a jacketed autoclave equipped with a stirrer, which wasalready washed, dried and substituted with nitrogen, were charged acyclohexane solution containing 10 parts by mass of pre-refinedbutadiene. Then, n-butyllithium and tetramethylethylenediamine wereadded and polymerization was carried out at 70° C. for 1 hour. Thepolymerization was continued for 1 hour after adding a cyclohexanesolution containing 17.5 parts by mass of pre-refined styrene.Subsequently, the polymerization was further continued for 1 hour afteradding a cyclohexane solution containing 55 parts by mass of pre-refinedbutadiene to the reaction system, and for 1 hour after further adding acyclohexane solution containing 17.5 parts by mass of styrene. Afterthat, methanol was added to stop the reaction and a block copolymerhaving a styrene content of 40 wt %, a 1,2-vinyl bond content inpolybutadiene parts of 50 wt % and a number-average molecular weight of150,000 was prepared.

[0121] 2-5) Polymer E

[0122] A polymerization was conducted in the same manner as in thepreparation of Polymer A except that addition amounts of n-butyllithiumand tetramethylethlenediamine were changed. A block copolymer having astyrene content of 70 wt %, a 1,2-vinyl bond content in polybutadieneparts of 30 wt % and a numberaverage molecular weight of 60,000 wasprepared.

[0123] 2-6) Polymer F

[0124] A polymerization was conducted in the same manner as in thepreparation of Polymer A except that an addition amount oftetramethylethlenediamine was increased and a polymerization temperaturewas set at 30° C. A block copolymer having a styrene content of 20 wt %,a 1,2-vinyl bond content in polybutadiene parts of 75 wt % and anumber-average molecular weight of 200,000 was prepared.

[0125] 2-7) Polymer G

[0126] In a jacketed autoclave equipped with a stirrer, which wasalready washed, dried and substituted with nitrogen, were charged acyclohexane solution containing 15 parts by mass of pre-refined styrene.Then, n-butyllithium was added and polymerization was carried out at 70°C. for 1 hour. The polymerization was continued for 1 hour after addinga cyclohexane solution containing 70 parts by mass of pre-refinedisoprene and further for 1 hour after adding a cyclohexane solutioncontaining 15 parts by mass of styrene. The obtained polymer was a blockcopolymer having a styrene content of 30 wt % and a total content ofvinyl bonds in polyisoprene parts of 5 wt %, and a number-averagemolecular weight of 350,000.

[0127] 2-8) Polymer H

[0128] A jacketed autoclave equipped with a stirrer was washed, driedand substituted with nitrogen. An n-hexane solution containing 20 wt %of pre-refined butadiene, an n-hexane solution of n-butyllithium and ann-hexane solution containing tetramethylethylenediamine were eachcontinuously supplied to the reactor from its bottom, and continuouspolymerization was carried out under the conditions of a reactiontemperature of 100° C. and a resident time of about 40 minutes. To theresultant polymer solution was added methanol to stop the reaction toprepare a polybutadiene polymer having a 1,2-vinyl bond content inpolybutadiene parts of 45 wt %, and a number-average molecular weight of300,000.

[0129] 2-9) Polymer I

[0130] In a jacketed autoclave equipped with a stirrer, which wasalready washed, dried and substituted with nitrogen, were charged acyclohexane solution containing 15 wt % of pre-refined butadiene. Afterthe temperature of the reactor was adjusted to 50° C., n-butyllithiumand tetramethylethylenediamine were added to carry out polymerizationfor about 30 minutes. At the time when the temperature in the reactorstopped rising, silica tetrachloride was added for coupling. Theobtained polymer was a polybutadiene having a 1,2-vinyl bond content inpolybutadiene parts of 40 wt %, and a molecular weight and content ofcoupled high molecular weight components of 450,000 and 75 wt %,respectively, and a molecular weight and content of uncoupled lowmolecular weight components of 120,000 and 25 wt %, respectively.

[0131] 2-10) Polymer J

[0132] After 4.3 tons of cychlohexane and 0.20 tons of a styrenemonomer-were charged in a 16 m³ reactor equipped with a stirrer, 4.8 kgof a 15 wt % n-butyllithium/n-hexane solution and further 0.62 kg oftetramethylethylenediamine were added to conduct polymerization at aninitial temperature of 70° C. for 40 minutes with stirring. Then, acyclohexane solution containing 0.924 tons of a 1,3-butadiene monomerwas added to continue polymerization for 1 hour. Further, a cyclohexanesolution containing 0.20 tons of a styrene monomer was added to furthercontinue polymerization for 40 minutes. The resultant polymer was astyrene-butadiene-styrene type block copolymer having a bound styrenecontent of 30 wt %, a block styrene content of 30 wt %, a 1,2-vinyl bondcontent in butadiene units of 37 wt % and a number-average molecularweight of about 230,000.

[0133] 2-11) Polymer K

[0134] After 3.88 tons of cyclohexane and 0.264 tons of a styrenemonomer were charged in a 16 m³ reactor equipped with a stirrer, 17 kgof a 15 wt % n-butyllithium/n-hexane solution and further 2.1 kg oftetramethylethylenediamine were added to conduct polymerization at aninitial temperature of 70° C. for 30 minutes with stirring. Then, acyclohexane solution containing 1.242 tons of a 1,3-butadiene monomerwas added to continue polymerization for 45 minutes. Further, acyclohexane solution containing 0.264 tons of styrene monomer was addedto further continue polymerization for 30 minutes. The resultant polymerwas a styrene-butadiene-styrene type block copolymer having a boundstyrene content of 30 wt %, a block styrene content of 30 wt %, a1,2-vinyl bond content in butadiene units of 51 wt % and anumber-average molecular weight of about 61,000.

[0135] 3) Preparation Examples of Hydrogenation Catalysts

[0136] As hydrogenation catalysts, solutions prepared by the followingmethods were used.

[0137] 3-1) Hydrogenation Catalyst I (TPM/Li)

[0138] Two liters of dried refined cyclohexane was charged in a reactorsubstituted with nitrogen, and 40 mmol ofbis(η⁵-cyclopentadienyl)titaniumdi(p-tolyl) and 150 g of1,2-polybutadiene having a molecular weight of about 1,000 (a content of1,2-vinyl bonds: about 85%) were dissolved therein. Then, a cyclohexanesolution containing 60 mmol of n-butyllithium was added to conduct areaction at room temperature for 5 minutes. Immediately after thereaction, 40 mmol of n-butanol was added with stirring, and theresultant solution was preserved at room temperature.

[0139] 3-2) Hydrogenation Catalyst II (Tebbe Reagent)

[0140] One liter of dried refined cyclohexane was charged in a reactorsubstituted with nitrogen, and 100 mmol ofbis(η⁵-cyclopentadienyl)titaniumdichloride was added thereto. To thesolution, a n-hexane solution containing 200 mmol of trimethyl aluminumwas added while sufficiently stirring to conduct a reaction at roomtemperature for about 3 days.

[0141] 3-3) Hydrogenation Catalyst III (TPM/Mg)

[0142] Two liters of dried refined cyclohexane was charged in a reactorsubstituted with nitrogen, and then 40 mmol of bis(η⁵-cyclopentadienyl)titaniumdi(p-tolyl) and 80 g of liquid1,2-polybutadiene having molecular weight of about 1,000 (1,2-vinyl bondcontent: about 85%) were dissolved therein. To the solution, acyclohexane solution containing 20 mmol of dibutylmagnesium was addedand the resultant solution was preserved at room temperature.

[0143] 3-4) Hydrogenation Catalyst IV (Tebbe Reagent)

[0144] A hydrogenation catalyst was prepared according to the methoddescribed in Japanese Patent Application Laid-Open No. 11-71426. 5 kg ofbis(η⁵-cyclopentadienyl)titaniumdichloride (TC) was added to 70.1 kg ofcyclohexane. After stirring, 24.9 kg of a 10% trimethylaluminum (TMAL)solution was added thereto. A reaction was carried out for 72 hours toprepare a hydrogenation catalyst (Tebbe reagent) solution.

[0145] 3-5) Hydrogenation Catalyst V (TPM/Li)

[0146] In addition, the hydrogenation catalyst was prepared according tothe method described in Japanese Patent Application Laid-Open No.8-33846. Namely, 6 kg ofbis(η⁵-cyclopentadienyl)titaniumdi(p-tolyl)(TPM) was dissolved to 526 kgof cyclohexane. After adding 60 kg of liquid 1,2-polybutadiene, 7.1 kgof a 15% butyllithium solution and further 0.6 kg of ethanol were added.A reaction was carried out to prepare a hydrogenation catalyst (TPM/Li).

Example 1

[0147] (Continuous Hydrogenation Process)

[0148] 10.5 liters of Polymer A solution comprising 1,576 g of thepolymer containing an olefinic unsaturated group was charged in a tankreactor equipped with a stirrer, which had an inner volume of 15 litersand an L/D of 3, and the temperature was increased to 70° C. After theinside of the reactor was substituted with hydrogen, the pressure in thereactor was increased to about 1 MPa (a gage pressure) in terms ofhydrogen. While stirring, the solution of Hydrogenation Catalyst I wassupplied to the reactor so that a Ti amount be 1.64 mmol, andsimultaneously hydrogen was supplied to the reactor over 1 hour so thatthe pressure in the reactor be 1 MPa. When a small amount of theresultant polymer was sampled, the degree of hydrogenation of olefinicunsaturated groups derived from butadiene was found to be 98%.

[0149] Subsequently, the Polymer A solution and the HydrogenationCatalyst I solution were supplied to the reactor from the top at a flowrate of about 120 ml/min (about 18 g/min in terms of a polymercontaining olefinic unsaturated groups) and at a flow rate such thatcontrols the Ti amount to be about 30 μmol/min, respectively. While, thesolution of the hydrogenated polymer was discharged from the bottom ofthe reactor at a flow rate of about 600 ml/min (about 90 g/min in termsof a polymer containing olefinic unsaturated groups) and then one partthereof was recycled to the reactor at the position L/4 above the lowertangent line thereof. The recycling amount was controlled so that themass ratio (Polymer A to be supplied to the reactor)/(the hydrogenatedpolymer to be recycled) was 1/4. The solution amount to be dischargedfrom the reactor at the bottom thereof was controlled so as to keep thesolution amount in the reactor about 10 liters. The hydrogenationtemperature was controlled by passing the hydrogenated polymer solutionto be recycled through a heat exchanger to cool down or, if necessary,heat up so as to keep the reactor temperature 90° C. The hydrogen wassupplied to the reactor from the bottom so that the pressure in thereactor be 1 MPa. The schematic flow of this process is shown in FIG. 1.

[0150] The hydrogenated polymer solution discharged from the reactor wassupplied to a deairing tank to deaerate the hydrogen contained thereinto prepare a hydrogenated polymer.

[0151] The above-described continuous hydrogenation was continued forabout 10 hours. The degree of hydrogenation of the hydrogenated polymerexhibited during the operation was extremely steady, that is, maintainedat from 97.5 to 99.5% throughout the continuous hydrogenation reaction.

Comparative Example 1

[0152] (Continuous Hydrogenation Process)

[0153] The continuous hydrogenation was conducted in the same manner asin Example 1 except that the hydrogenated polymer discharged from thebottom of the reactor was not recycled. The schematic flow of thisprocess is shown in FIG. 2. Although the reaction was designed so as tocontrol the temperature of the hydrogenation reaction by the jacketattached to the reactor, the reaction temperature was increased and itwas hard to control the temperature at a stable level. In addition, thedegree of hydrogenation of the hydrogenated polymer prepared in thecontinuous hydrogenation reaction was from 85 to 93%. The hydrogenationreaction was not conducted steadily.

Example 2

[0154] (Continuous Hydrogenation Process)

[0155] 10.5 liters of Polymer B solution comprising 1,576 g of thepolymer containing an olefinic unsaturated group was charged in a tankreactor equipped with a stirrer, which had an inner volume of 15 litersand an L/D of 3, and the temperature was increased to 70° C. After theinside of the reactor was substituted with hydrogen, the pressure in thereactor was increased to about 1 MPa (a gage pressure) in terms ofhydrogen. While stirring, the solution of Hydrogenation Catalyst I wassupplied to the reactor so that the Ti amount be 3.28 mmol, andsimultaneously hydrogen was supplied to the reactor over 1 hour so thatthe hydrogen pressure in the reactor be 1 MPa. When a small amount ofthe resultant polymer was sampled, the degree of hydrogenation ofolefinic unsaturated groups derived from butadiene was found to be 98%.

[0156] Subsequently, the continuous hydrogenation reaction by tworeactors connected in series was conducted using the above-mentionedreactor as a first reactor and a tank reactor equipped with a stirrer,which had an inner volume of 15 liters and an L/D of 6 as a secondreactor.

[0157] Firstly, the Polymer B solution and the solution of HydrogenationCatalyst I were supplied to the first reactor from the top at a flowrate of about 100 ml/min (about 15 g/min in terms of the polymercontaining olefinic unsaturated groups) and at a flow rate such thatcontrols the Ti amount to be about 22 μmol/min, respectively. At thesame time, the solution of the hydrogenated polymer was discharged fromthe bottom of the above-mentioned reactor at a flow rate of about 2liters/min (about 300 g/min in terms of the polymer containing olefinicunsaturated groups) and one part thereof was recycled to the firstreactor at the position L/2 above the lower tangent line thereof. Therecycling amount was controlled so that the mass ratio (Polymer B to besupplied to the reactor)/(the hydrogenated polymer to be recycled) was1/19. The solution amount to be discharged from the bottom of the firstreactor was controlled so that the amount of solution in the firstreactor be kept about 10 liters. The hydrogenation reaction temperaturewas controlled by passing the hydrogenated polymer solution to berecycled through a heat exchanger to cool down or, if necessary, heat upso as to keep the reactor temperature 110° C. The hydrogen was suppliedto the first reactor from the bottom so that the pressure in the reactorbe 1 MPa.

[0158] The hydrogenated polymer solution discharged from the firstreactor was supplied to the second reactor from the top, and at the sametime a polymer solution hydrogenated in the second reactor wasdischarged from the bottom at a flow rate of about 100 ml/min (about 15g/min in terms of the polymer containing olefinic unsaturated groups).The amount of the hydrogenated polymer solution discharged from thebottom of the second reactor was controlled so that the solution amountin the second reactor be kept about 10 liters.

[0159] In the above operation, the hydrogenated polymer solutiondischarged from the first reactor was supplied to the second reactorafter being mixed with the solution of Hydrogenation Catalyst I whichwas added thereto at a flow rate of about 8 μmol/min. The reactiontemperature was controlled by the jacket attached to the second reactorso as to keep the reactor temperature 110° C. The hydrogen was suppliedto the second reactor from the bottom so that the pressure in thereactor be 1 MPa. The schematic flow of this process is shown in FIG. 3.

[0160] The hydrogenated polymer solution being discharged from thesecond reactor was supplied to a deairing tank to deaerate the hydrogencontained therein to prepare a hydrogenated polymer.

[0161] The above-mentioned continuous hydrogenation was continued forabout 10 hours. The degrees of hydrogenation of the polymer hydrogenatedin the first and second reactors were extremely steady, that is,maintained from 80 to 93% and from 97.5 to 99.5%, respectively,throughout the reaction.

Example 3

[0162] (Continuous Hydrogenation Process)

[0163] 10.5 liters of Polymer C solution comprising 1,576 g of thepolymer containing olefinic unsaturated groups was charged in a tankreactor equipped with a stirrer, which had an inner volume of 15 litersand an L/D of 3, and the temperature was increased to 70° C. After theinside of the reactor was substituted with hydrogen, the pressure in thereactor was increased to about 1 MPa (a gage pressure) in terms ofhydrogen. While stirring, the solution of Hydrogenation Catalyst II wassupplied to the reactor so that the Ti amount be 1.64 mmol, and hydrogenwas supplied to the reactor over 1 hour so that the pressure in thereactor be 1 MPa. When a small amount of the resultant polymer wassampled, the degree of hydrogenation of olefinic unsaturated groupsderived from butadiene was found to be 98%.

[0164] Subsequently, the continuous hydrogenation reaction by tworeactors connected in series was conducted using the above-mentionedreactor as a first reactor and a tube reactor having an inner volume of10 liters and an L/D of 15 as a second reactor. In the tube reactor, astatic mixer was arranged.

[0165] Firstly, the Polymer C solution and the solution of HydrogenationCatalyst II were supplied to the first reactor from the top at a flowrate of about 180 ml/min (about 27 g/min in terms of the polymercontaining olefinic unsaturated groups) and at a flow rate such thatcontrols the Ti amount to be about 17 μmol/min, respectively. At thesame time, the solution of the hydrogenated polymer was discharged fromthe bottom of the reactor at a flow rate of about 760 ml/min (about 108g/min in terms of the polymer containing olefinic unsaturated groups)and then one part thereof was recycled to the first reactor at theposition L/4 above the lower tangent line thereof. The recycling amountwas controlled so that the mass ratio (Polymer C to be supplied to thereactor)/(the hydrogenated polymer to be recycled) was 1/3. The solutionamount to be discharged from the bottom of the first reactor wascontrolled so that the amount of the solution in the first reactor bekept about 10 liters. The hydrogenation temperature was controlled bypassing the hydrogenated polymer solution to be recycled through a heatexchanger to cool down or, if necessary, heat up so as to keep thereactor temperature 90° C. The hydrogen was supplied to the firstreactor from the bottom so that the pressure in the reactor be 1.5 MPa.

[0166] The hydrogenated polymer solution being discharged from the firstreactor was supplied to the second reactor from the bottom, and at thesame time a polymer solution hydrogenated in the second reactor wasdischarged from the top at a flow rate of about 760 ml/min (about 108g/min in terms of the polymer containing olefinic unsaturated groups)and one part thereof was recycled to the second reactor at the lowerportion thereof. The recycling amount was controlled so that the massratio (Polymer C to be supplied to the reactor)/(the hydrogenatedpolymer to be recycled) was 1/3. In the above operation, thehydrogenated polymer solution discharged from the first reactor wassupplied to the second reactor after being mixed with the solution ofHydrogenation Catalyst II added thereto at a flow rate such thatcontrols the Ti amount to be about 8 μmol/min. The reaction temperaturewas controlled by passing the hydrogenated polymer solution to berecycled through a heat exchanger to cool down or, if necessary, heat upso as to keep the reactor temperature 90° C. The hydrogen was suppliedto the second reactor from the bottom so that the pressure in thereactor was 1.5 MPa. The schematic flow of this process is shown in FIG.4.

[0167] The hydrogenated polymer solution discharged from the secondreactor was supplied to a deairing tank to deaerate the hydrogencontained therein to prepare a hydrogenated polymer.

[0168] The above-mentioned continuous hydrogenation was continued forabout 10 hours. The degrees of hydrogenation of the polymer hydrogenatedin the first and second reactors were extremely steady, that is,maintained from 85 to 95% and 98% or more, respectively, throughout thecontinuous hydrogenation reaction.

Example 4

[0169] (Continuous Hydrogenation Process)

[0170] 10.5 liters of Polymer D solution comprising 1,576 g of thepolymer containing olefinic unsaturated groups was charged in a tankreactor equipped with a stirrer, which had an inner volume of 15 litersand an L/D of 3, and the temperature was increased to 70° C. After theinside of the reactor was substituted with hydrogen, the pressure in thereactor was increased to about 1 MPa (a gage pressure) in terms ofhydrogen. While stirring, the solution of Hydrogenation Catalyst II wassupplied to the reactor so that the Ti amount be 1.64 mmol, and hydrogenwas supplied to the reactor over 1 hour so that the pressure in thereactor be 1 MPa. When a small amount of the resultant polymer wassampled, the degree of hydrogenation of olefinic unsaturated groupsderived from butadiene was found to be 98%.

[0171] Subsequently, the continuous hydrogenation reaction by threereactors connected in series was conducted using the above-mentionedreactor as a first reactor, a tank reactor equipped with a stirrer whichhad an inner volume of 15 liters and an L/D of 3 as a second reactor,and a tube reactor having an inner volume of 10 liters and an L/D of 15as a third reactor.

[0172] Firstly, the Polymer D solution and the solution of HydrogenationCatalyst II were supplied to the first reactor from the top at a flowrate of about 180 ml/min (about 27 g/min in terms of the polymercontaining olefinic unsaturated groups) and at a flow amount such thatcontrols the Ti amount to be about 12 μmol/min, respectively. At thesame time, the solution of the hydrogenated polymer was discharged fromthe bottom of the reactor at a flow rate of about 1.8 liters/min (about270 g/min in terms of the polymer containing olefinic unsaturatedgroups) and one part thereof was recycled to the first reactor at theposition L/8 above the lower tangent line thereof. The recycling amountwas controlled so that the mass ratio (Polymer D to be supplied to thereactor)/(the hydrogenated polymer to be recycled) was 1/9. The solutionamount to be discharged from the bottom of the first reactor wascontrolled so that the amount of the solution in the first reactor wascontrolled to be about 10 liters . The hydrogenation temperature wascontrolled by passing the hydrogenated polymer solution to be recycledthrough a heat exchanger to cool down or, if necessary, heat up so as tokeep the first reactor temperature 110° C. The hydrogen was supplied tothe first reactor from the bottom so that the pressure in the reactor be1 MPa.

[0173] The hydrogenated polymer solution discharged from the firstreactor was supplied to the second reactor from the top, and at the sametime a polymer solution hydrogenated in the second reactor wasdischarged from the bottom thereof at a flow rate of about 760 ml/min(about 108 g/min in terms of the polymer containing olefinic unsaturatedgroup) and one part thereof was recycled to the second reactor at theposition L/8 above the lower tangent line thereof. The recycling amountwas controlled so that the mass ratio (Polymer D to be supplied to thereactor)/(the hydrogenated polymer to be recycled) was 1/3. The amountof the hydrogenated polymer solution to be discharged from the bottom ofthe second reactor was controlled so that the amount of the solution inthe second reactor be kept about 10 liters . In the above operation, thehydrogenated polymer solution discharged from the first reactor wassupplied to the second reactor after being mixed with the solution ofHydrogenation Catalyst II which was added thereto at a flow rate suchthat controls the Ti amount to be about 6 μmol/min. The reactiontemperature was controlled by passing the hydrogenated polymer solutionto be recycled through a heat exchanger to cool down or, if necessary,heat up so as to keep the second reactor temperature 110° C. Thehydrogen was supplied to the second reactor from the bottom so that thepressure in the reactor be 1 MPa.

[0174] The hydrogenated polymer solution discharged from the secondreactor was supplied to the third reactor from the bottom, and at thesame time a hydrogenated polymer solution therein was discharged fromthe top of the third reactor at a flow rate of about 180 ml/min (about27 g/min in terms of the polymer containing olefinic unsaturatedgroups). The hydrogenation reaction temperature was controlled by thejacket attached to the third reactor so as to keep the reactortemperature 110° C. The hydrogen was supplied to the third reactor fromthe bottom so that the pressure in the reactor be kept 1 MPa. Theschematic flow of this process is shown in FIG. 5.

[0175] The hydrogenated polymer solution being discharged from the thirdreactor was supplied to a deairing tank to deaerate the hydrogencontained therein to prepare the hydrogenated polymer.

[0176] The above-mentioned continuous hydrogenation was continued forabout 10 hours. The degrees of hydrogenation of the polymer hydrogenatedin the first, second, and third reactors were extremely steady, that is,maintained from 75 to 85%, from 90 to 95%, and 98% or more,respectively, throughout the continuous hydrogenation reaction.

Example 5

[0177] (Continuous Hydrogenation Process)

[0178] 10.5 liters of Polymer H solution comprising 1,386 g of thepolymer containing of olefinic unsaturated groups was charged in a tankreactor equipped with a stirrer, which had an inner volume of 15 litersand an L/D of 3, and the temperature was increased to 70° C. After theinside of the reactor was substituted with hydrogen, the pressure in thereactor was increased to about 1 MPa (a gage pressure) in terms ofhydrogen. While stirring, the solution of Hydrogenation Catalyst II wassupplied to the reactor so that the Ti amount be 1.64 mmol, and hydrogenwas supplied to the reactor over 1 hour so that hydrogen pressure be 1MPa. When a small amount of the resultant polymer was sampled, thedegree of hydrogenation of olefinic unsaturated groups derived frombutadiene was found to be 98%.

[0179] Subsequently, the continuous hydrogenation reaction by tworeactors connected in series was conducted using the above-mentionedreactor as a first reactor and a tube reactor having an inner volume of10 liters and an L/D of 15 as a second reactor. In the tube reactor, astatic mixer was arranged.

[0180] Firstly, while continuously polymerizing Polymer H, the solutionof polymerized Polymer H and the solution of Hydrogenation Catalyst IIwere supplied to the first reactor from the top at a flow rate of about200 ml/min (about 26 g/min in terms of the polymer containing olefinicunsaturated groups) and at a flow rate such that controls the Ti amountto be about 12 μmol/min, respectively. And, the solution of thehydrogenated polymer was discharged from the bottom of the first reactorat a flow rate of about 3.2 liters/min (about 422 g/min in terms of thepolymer containing olefinic unsaturated groups), and then one partthereof was recycled to the first reactor at the position L/8 above thelower tangent line thereof. The recycling amount was controlled so thatthe mass ratio (Polymer H to be supplied to the reactor)/(thehydrogenated polymer to be recycled) was 1/15. The solution amount to bedischarged from the bottom of the first reactor was controlled so thatthe amount of solution in the first reactor be kept about 10 liters .The hydrogenation temperature was controlled by passing the hydrogenatedpolymer solution to be recycled through a heat exchanger to cool downor, if necessary, heat up so as to keep the reactor temperature 90° C.The hydrogen was supplied to the first reactor from the bottom so thatthe pressure in the reactor be 1 MPa.

[0181] The hydrogenated polymer solution being discharged from the firstreactor was supplied to the second reactor from the bottom. In theabove-mentioned operation, the hydrogenated polymer solution beingdischarged from the first reactor was supplied to the second reactorafter being mixed with the solution of Hydrogenation Catalyst II whichwas added thereto at a flow amount such that controls the Ti amount tobe about 6 μmol/min. The temperature of the hydrogenation reaction wascontrolled by the jacket attached to the second reactor so as to keepthe reactor temperature 90° C. The hydrogen was supplied to the secondreactor from the bottom so that the pressure in the reactor be 1 MPa.The schematic flow of this process is shown in FIG. 6.

[0182] The hydrogenated polymer solution being discharged from thesecond reactor was supplied to a deairing tank to deaerate the hydrogencontained therein to prepare a hydrogenated polymer.

[0183] The above-mentioned continuous hydrogenation was continued overabout 10 hours. The degrees of hydrogenation of the polymer hydrogenatedin the first and second reactors were extremely steady, that is,maintained from 85 to 95% and 98% or more respectively throughout thecontinuous hydrogenation reaction.

Example 6

[0184] (Continuous Hydrogenation Process)

[0185] According to the following process, a hydrogenated polymer, thedegree of hydrogenation of which was controlled about 40%, wascontinuously prepared.

[0186] Firstly, 10.5 liters of Polymer I solution comprising 1,244 g ofthe polymer containing olefinic unsaturated groups was charged in a tankreactor equipped with a stirrer, which had an inner volume of 15 litersand an L/D of 3, and the temperature was increased to 70° C. After theinside of the reactor was substituted with hydrogen, the pressure in thereactor was increased to about 1 MPa (a gage pressure) in terms ofhydrogen. While stirring, the solution of Hydrogenation Catalyst I wassupplied to the reactor so that the Ti amount be 0.66 mmol, and hydrogenwas supplied so that the degree of hydrogenation of olefinic unsaturatedgroups derived from butadiene be about 40% to conduct a hydrogenationreaction.

[0187] Subsequently, the Polymer I solution and the solution ofHydrogenation Catalyst I were supplied to the above-mentioned reactorfrom the top at a flow rate of about 200 ml/min (about 24 g/min in termsof the polymer containing olefinic unsaturated groups) and at a flowrate such that controls the Ti amount to be about 12 μmol, respectively.While, the solution of hydrogenated polymer was discharged from thebottom of the reactor at a flow amount of about 220 ml/min (about 26g/min in terms of the polymer containing olefinic unsaturated groups),and then one part thereof was recycled to the reactor at the positionL/4 above the lower tangent line thereof. The recycling amount wascontrolled so that the mass ratio (Polymer I to be supplied to thereactor)/(the hydrogenated polymer to be recycled) was 10/1. Thesolution amount to be discharged from the bottom of the reactor wascontrolled so as to keep the amount of solution in the reactor about 10liters . The hydrogenation temperature was controlled by passing thehydrogenated polymer solution to be recycled through a heat exchanger tocool down or, if necessary, heat up so as to keep the reactortemperature 90° C. The amount of hydrogen to be supplied to the reactorfrom the bottom was about 40% of that necessary to completelyhydrogenate the olefinic unsaturated groups of the Polymer I to besupplied to the continuous hydrogenation reactor, i.e., at a flow rateof 0.178 mol/min. The pressure of the continuous hydrogenation reactorwas about from 0.5 to 1 MPa. The schematic flow of this process is shownin FIG. 1.

[0188] The hydrogenated polymer solution being discharged from thereactor was supplied to a deairing tank to deaerate the hydrogencontained therein to prepare a hydrogenated polymer.

[0189] The above-mentioned continuous hydrogenation was continued forabout 10 hours. The degrees of hydrogenation of the hydrogenated polymerwhich was obtained during this method was extremely steady, that is,maintained from 35 to 45% throughout the continuous hydrogenationreaction.

Example 7

[0190] (Continuous Hydrogenation Process)

[0191] According to the following process, a hydrogenated polymer, thedegree of hydrogenation of which was controlled about 55%, wascontinuously prepared.

[0192] The continuous hydrogenation reaction was conducted in the samemanner as in Example 2 except that Polymer E was used instead of PolymerB and the total amount of hydrogen added was about 55% of that necessaryto completely hydrogenate the olefinic unsaturated groups of the PolymerE to be supplied to the continuous hydrogenation reactor, i.e., at aflow rate of 0.046 mol/min. The pressure of the continuous hydrogenationreactor was about from 0.5 to 1 MPa.

[0193] The above-mentioned continuous hydrogenation was continued forabout 10 hours. The degree of hydrogenation of the polymer beinghydrogenated in the first and second reactors was extremely steady, thatis, maintained from 28 to 38% and from 50 to 60%, respectively,throughout the continuous hydrogenation reaction.

Example 8

[0194] (Continuous Hydrogenation Process)

[0195] The continuous hydrogenation reaction was conducted for about 10hours in the same manner as in Example 3 except that Polymer F was usedinstead of Polymer C. The degree of the hydrogenation of polymer beinghydrogenated in the first reactor and second reactor was extremelysteady, that is, maintained from 85 to 95% and 98% or more,respectively, throughout the continuous hydrogenation reaction.

Example 9

[0196] (Continuous Hydrogenation Process)

[0197] The continuous hydrogenation reaction was conducted for about 10hours in the same manner as in Example 2 except that Polymer G andHydrogenation Catalyst III were used instead of Polymer B andHydrogenation Catalyst I, respectively. The degrees of hydrogenation ofthe polymer hydrogenated in the first and second reactors were extremelysteady, that is, maintained from 80 to 93% and 97% or more,respectively, throughout the continuous hydrogenation reaction.

Example 10

[0198] (Continuous Hydrogenation Process)

[0199] According to the following process, the hydrogenated polymer, thedegree of hydrogenation of which was controlled to be about 70%, wascontinuously prepared.

[0200] The continuous hydrogenation reaction was conducted in the samemanner as in Example 1 except that the amount of hydrogen added wasabout 70% of that necessary to completely hydrogenate the olefinicunsaturated groups of the Polymer A (0.187 mol/min) and the recyclingamount was controlled so that the mass ratio (Polymer A to be suppliedto the reactor)/(the hydrogenated polymer to be recycled) be 1/15. Thepressure of the continuous hydrogenation reactor was about from 0.5 to 1MPa.

[0201] The above-mentioned continuous hydrogenation was continued forabout 10 hours. The degrees of hydrogenation of the polymer hydrogenatedwere extremely steady, that is, maintained from 65 to 75% throughout thecontinuous hydrogenation reaction.

Example 11

[0202] (Continuous Hydrogenation Process)

[0203] In the continuous hydrogenation reaction in Example 2, the flowrate of the hydrogenated polymer solution to be discharged from thebottom of the first reactor was changed to about 2.2 liters/min and onepart thereof was recycled to the first reactor from the top. Therecycling amount was controlled so that the mass ratio (Polymer B to besupplied to the first reactor)/(the hydrogenated polymer to be recycled)was 1/10. Further, one part of the hydrogenated polymer solutiondischarged from the second reactor was recycled to the second reactor atthe position of L/2 above the lower tangent line thereof at a flow rateof about 100 ml/min, i.e., at a mass ratio (Polymer B to be supplied tothe first reactor)/(the hydrogenated polymer to be recycled) of 1/1. Thecontinuous hydrogenation reaction was conducted in the same manner as inExample 2 except for the above. The schematic flow of this process isshown in FIG. 7.

[0204] The above-mentioned continuous hydrogenation was continued forabout 10 hours. The degrees of hydrogenation of the polymer beinghydrogenated were extremely steady, that is, maintained 98% or morethroughout the continuous hydrogenation reaction.

Example 12

[0205] (Batch Hydrogenation Process)

[0206] Ethyl alcohol was added in an amount 0.9 times as large as themole number of n-butyllithium, i.e., in an amount of 10.1 moles, to thePolymer J for a pre-treatment and then the whole amount of the resultantpolymer solution was transferred to a tank reactor equipped with astirrer and having an inner volume of 20 m³ and an L/D of 3. Further, tothe reactor was added the cyclohexane refined and dried to prepare a 12wt. % cyclohexane solution, and then the initial temperature in thereactor was set at 80° C. under stirring. Subsequently, the polymersolution was discharged from the bottom of the reactor and the totalamount thereof was recycled at a flow rate of 150 m³/hr through arecycling line (equipped with a heat exchanger), which could recycle thedischarged solution to the reactor at the position of L/8 above thelower tangent line thereof. This recycling operation was continued untilthe reaction completed. The inside of the reactor was substituted withhydrogen gas and pressurized to be a hydrogen pressure of 0.7 MPa. Tothe polymer solution was added Hydrogenation Catalyst V (TPM/Li) so thatthe mass ratio of Ti to the polymer be 20 wt ppm (corresponding to 0.55moles of Ti) to start the hydrogenation. Two minutes later from theinitiation of the hydrogenation reaction, the absorption rate ofhydrogen became stable and reached 7.2 Nm³/min. Herein, the term “Nm³ ”represents a volume under the normal conditions (the same applied to thebelow). At the time when the absorption rate of hydrogen decreased to5.0 Nm³/min, 70% of the initial rate, 20 wt ppm of the catalyst(corresponding to 0.55 moles of Ti) was additionally supplied. Thedegree of hydrogenation of the polymer at this time was 85.4% based onthe consumption of the hydrogen gas. The hydrogenation reaction wasfurther continued. The degree of hydrogenation of the polymer based onthe consumption of the hydrogen gas reached 100% and the absorption ofhydrogen to the polymer solution was stopped. Consequently, thehydrogenation reaction was stopped. The degree of hydrogenation of thepolymer measured by the NMR method was 99.7%. The highest temperatureduring the hydrogenation was 92° C. and the reaction time was 42minutes.

Comparative Example 2

[0207] (Batch Hydrogenation Process)

[0208] The hydrogenation reaction was conducted in the same manner as inExample 12 except that the recycle line was not used. The degree ofhydrogenation of the polymer at the time of additional supply was 72.4%based on the consumption of the hydrogen gas. Even at the point where ithad been 1 hour since the initiation of the reaction, the degree ofhydrogenation of the polymer based on the consumption of the hydrogengas was 88.1%, and the reaction did not make any further progress. Thereaction heat was generated in a too considerable amount to reducesufficiently. The highest temperature during the hydrogenation reactionreached to 123° C.

Example 13

[0209] (Batch Hydrogenation Process)

[0210] Ethyl alcohol was added in an amount 0.9 times as large as themole number of n-butyllithium, i.e., in an amount of 10.1 moles, to thePolymer J for a pre-treatment and then the whole amount of the resultantpolymer solution was transferred to a tank reactor equipped with astirrer and having an inner volume of 20 m³ and an L/D of 3. Further, tothe reactor was added the cyclohexane refined and dried to prepare a 12wt % cyclohexane solution, and then the initial temperature in thereactor was set at 80° C. under stirring. Subsequently, the polymersolution was discharged from the bottom of the reactor and the totalamount thereof was recycled at a flow rate of 150 m³/hr through arecycling line (equipped with a heat exchanger), which could recycle thedischarged solution to the reactor at the position of L/8 above thelower tangent line thereof. This recycling operation was continued untilthe reaction completed. The inside of the reactor was substituted withhydrogen gas and pressurized to be a hydrogen pressure of 0.7 MPa. Tothe polymer solution was added Hydrogenation Catalyst V (TPM/Li) so thatthe mass ratio of Ti to the polymer be 15 wt ppm (corresponding to 0.41moles of Ti) to start the hydrogenation. Two minutes later from theinitiation of the hydrogenation reaction, the absorption rate ofhydrogen became stable and reached 5.8 Nm³/min.

[0211] At the time when the absorption rate of hydrogen decreased to 70%of the initial rate, i.e., at a flow rate of 4.1 Nm³/min, 10 wt ppm ofthe catalyst (corresponding to 0.28 moles of Ti) was additionallysupplied. The degree of hydrogenation of the polymer at this time was80.1% based on the consumption of the hydrogen gas. Again, theabsorption rate decreased to 70% of the initial rate, i.e., at a flowrate of 4.1 Nm³/min, 5 wt ppm of the catalyst (corresponding to 0.14moles of Ti) was additionally supplied. The degree of hydrogenation ofthe polymer based on the consumption of the hydrogen gas at this timewas 94.5%. The hydrogenation reaction was further continued. The degreeof hydrogenation of the polymer based on the consumption of the hydrogengas reached 100% and the absorption of hydrogen to the polymer solutionwas stopped. Consequently, the hydrogenation reaction was stopped. Thedegree of hydrogenation of the polymer measured by the NMR method was99.9%. The highest temperature during the hydrogenation was 90° C. andthe reaction time was 39 minutes.

Example 14

[0212] (Batch Hydrogenation Process)

[0213] Trimethylchlorosilane was added in an amount 0.9 times as largeas the mole number of n-butyllithium, i.e., in an amount of 35.8 moles,to the Polymer K for a pre-treatment and then the whole amount of theresultant polymer solution was transferred to a tank reactor equippedwith a stirrer and having an inner volume of 20 m³ and an L/D of 3.Further, to the reactor equipped with a stirrer was added thecyclohexane refined and dried to prepare a 17 wt % cyclohexane solutionand then the initial temperature in the reactor was set at 80° C. whilestirring. Subsequently, the polymer solution was discharged from thebottom of the reactor and the total amount thereof was recycled at aflow rate of 150 m³/hr through a recycling line (equipped with a heatexchanger), which could recycle the discharged solution to the reactorat the position of L/8 above the lower tangent line thereof. Thisrecycling operation was continued until the reaction completed. Theinside of the reactor was substituted with hydrogen gas and pressurizedto be a hydrogen pressure of 0.7 MPa. To the polymer solution in thereactor was added Hydrogenation Catalyst IV (Tebbe reagent) so that themass ratio of Ti to the polymer be 12 wt ppm (corresponding to 0.44moles of Ti) to start the hydrogenation. Two minutes later from theinitiation of the hydrogenation reaction, the absorption rate ofhydrogen became stable and reached 6.3 Nm³/min. At the time when theabsorption rate of hydrogen decreased to 3.2 Nm³/min, 50% of the initialrate, 5 wt ppm of the catalyst (Hydrogenation Catalyst IV)(corresponding to 0.18 moles of Ti) was additionally supplied. Thedegree of hydrogenation of the polymer at this time was 82.0% based onthe consumption of the hydrogen gas. Again, the absorption rate reacheddecreased to 3.2 Nm³/min, 50% of the initial rate, and 5 wt ppm of thecatalyst (Hydrogenation Catalyst IV)(corresponding to 0.18 moles of Ti)was additionally supplied. The degree of hydrogenation of the polymerbased on the consumption of the hydrogen gas at this time was 91.1%.Further, at the time when the absorption rate reached decreased to 3.2Nm³/min, 50% of the initial rate, 3 wt ppm of the catalyst(Hydrogenation Catalyst IV)(corresponding to 0.11 moles of Ti) wasadditionally supplied. The degree of hydrogenation of the polymer basedon the consumption of the hydrogen gas at this time was 97.5%. Thehydrogenation reaction was further continued. The degree ofhydrogenation of the polymer based on the consumption of the hydrogengas reached 100% and the absorption of hydrogen to the polymer solutionwas stopped. Consequently, the hydrogenation reaction was stopped. Thedegree of hydrogenation of the polymer measured by the NMR method was100%. The highest temperature during the hydrogenation was 90° C. andthe reaction time was 38 minutes.

[0214] Industrial Applicability

[0215] According to the present invention, a hydrogenated polymer havinga desirable degree of hydrogenation can be steadily obtained for a longterm in a process wherein a polymer containing a olefinic unsaturatedgroup is contacted with hydrogen to hydrogenate the olefinic unsaturatedgroup. As a result, the amount of the catalyst to be used can bedecreased more sufficiently than in the conventional process.

[0216] The hydrogenated polymer prepared according to the process of thepresent invention can be used as it is or as a composition incorporatingvarious additives, for various molded articles such as injection molded,blow molded, compression molded, vacuum formed or extrusion moldedarticles in the shape of a sheet, a film or the like, or molded articlesin the shape of non-woven cloth or fibers, or the like. These moldedarticles can be used for food packaging materials, materials for medicaldevice, home electric appliances and parts thereof , materials forautomobile parts, industrial parts, utensils, toys or the like, footwearmaterials, materials for adhesive or bonding agents, asphalt modifier orthe like.

What is claimed is:
 1. A process for hydrogenating a polymer, whichprocess comprises the steps of: contacting a polymer solution containingan olefinic unsaturated group with hydrogen in the presence of ahydrogenation catalyst to hydrogenate the olefinic unsaturated group ofthe polymer; and recycling at least one part of the resultanthydrogenated polymer solution for hydrogenation.
 2. The processaccording to claim 1, wherein the polymer solution containing anolefinic unsaturated group is continuously supplied to a reactor tocontinuously hydrogenate the olefinic unsaturated group of the polymer,and the resultant hydrogenated polymer solution is continuously takenout from the reactor and then one part thereof is continuously recycledto the reactor for hydrogenation.
 3. The process according to claim 2,wherein the hydrogen is supplied from near the bottom of the reactor. 4.The process according to claim 2, wherein the reactor is a tank reactor,the polymer solution containing an olefinic unsaturated group issupplied from near the top of the reactor, and the resultanthydrogenated polymer solution is taken out from near the bottom of thereactor or a piping arranged out of the reactor to recycle one partthereof to the reactor for hydrogenation.
 5. The process according toclaim 2, wherein the reactor is a tank reactor having an L/D of from 1to 8 and being equipped with a stirrer wherein L represents a lengthbetween an upper tangent line and a lower tangent line of the reactorand D represents an inner diameter of the reactor.
 6. The processaccording to claim 2, wherein the reactor is a column or tube reactor,and the polymer solution containing an olefinic unsaturated group issupplied from near the bottom of the reactor, and one part of thepolymer solution hydrogenated in the reactor is continuously taken outfrom near the top of the reactor or a piping arranged out of the reactorto recycle one part thereof to the reactor.
 7. The process according toclaim 1, wherein the hydrogenation catalyst is supplied two or moretimes to conduct hydrogenation.
 8. The process according to claim 1,wherein a reactor group comprising two or more reactors connected inseries is used, the polymer solution containing an olefinic unsaturatedgroup is continuously supplied to the first reactor of the reactorgroup, the hydrogen is supplied to at least one reactor of the reactorgroup to continuously hydrogenate the olefinic unsaturated group of thepolymer, and the resultant polymer solution hydrogenated in at least onereactor of the reactor group is continuously taken out to continuouslyrecycle one part thereof to the reactor and/or a reactor arrangedupstream of the reactor for hydrogenation.
 9. The process according toclaim 8, wherein the hydrogen is supplied from near the bottom of atleast one reactor of the reactor group.
 10. The process according toclaim 8, wherein the first reactor is a tank reactor having an L/D offrom 1 to 8 and being equipped with a stirrer, and the second andfollowing reactors arranged downstream of the first reactor are at leastone kind selected from the group consisting of a tank reactor having anL/D of from 1 to 8 and being equipped with a stirrer, a column reactorhaving an L/D of 2 or more and a tube reactor having an L/D of 2 ormore.
 11. The process according to claim 8, wherein the hydrogencatalyst is supplied to the first reactor and is additionally suppliedto at least one of the reactors arranged downstream of the firstreactor.
 12. The process according to claim 2 or 8, wherein thecontinuous hydrogenation is initiated after the polymer solutioncontaining an olefinic unsaturated group is hydrogenated to a desirabledegree of hydrogenation.
 13. The process according to any one of claims1 through 11, wherein a mass ratio between a polymer containing anolefinic unsaturated group to be supplied and the resultant hydrogenatedpolymer to be recycled is from 1/50 to 50/1.
 14. The process accordingto claim 1, wherein a hydrogenation reaction is a batch type.
 15. Theprocess according to claim 14, wherein the hydrogenation catalyst issupplied two or more times.
 16. The process according to claim 15,wherein timing of the second and following supply of the hydrogenationcatalyst is decided by measuring an absorption rate of hydrogen.
 17. Theprocess for according to claim 16, wherein timing of the second andfollowing supply is a time when the absorption rate of hydrogendecreases to 80% or less of an initial absorption rate of hydrogen atthe beginning of hydrogenation reaction.
 18. The process according toclaim 15, wherein an amount of the first supply of hydrogenationcatalyst is controlled so that a degree of hydrogenation at the time ofthe second and following supply is from 50% to 90%.
 19. The processaccording to any one of claims 1 through 11 and 14 through 18, whereinthe resultant hydrogenated polymer solution is recycled through a heatexchanger.
 20. The process according to any one of claims 1, 7, 11, and15 through 18, wherein the hydrogenation catalyst is a metallocenecompound.